LS3 water neck and radiator hose
 

Want to make sure this water neck will fit on the BOTTOM outlet on my LS3

Also - any suggestions for the upper and lower radiator hoses ?

Re: LS3 water neck and radiator hose
 

I don't know about the thermostat housing but in regards to the radiator hoses I make a wire pattern and then hit the parts stores. Most will let you look thru them to find what you need.
Just a note. The earlier LS engines had a "fixed" thermostat in the housing. The later LS housings have removeable thermostats.

Re: LS3 water neck and radiator hose
 

That listing shows 1997 - 2020 LS engines, but they changed the thermostat design in 2014 or so. Maybe they made the new ones universal? I had to mill open the diameter where the thermostat sits about .050" on the diameter to get the earlier version to work with the later thermostat.

Re: LS3 water neck and radiator hose
 

Does the thermostat typically go into the lower hose or the upper ?

Re: LS3 water neck and radiator hose
 

Always in the lower on LS engines. See pic of my 68 C10 LS swap.
SBC had the stat in the upper hose.

Re: LS3 water neck and radiator hose
 

impressed you got the coil installed without the spindle on.

Re: LS3 water neck and radiator hose
 

Good thing about lowering springs that it makes it so much easier to install the spring and then the spindle.

Re: LS3 water neck and radiator hose
 

Back to the top

Thermostat housing is on now just to find the upper and lower hoses

I have searched a few times - seems most suggest the Upper hose to be a Gates 21439 but that has the water neck that comes up and out at like a 40 degree angle, my LS3 has it coming out totally different.

I also couldn't find a clear answer on if the lower hose Gates 21439 had the correct end sizes ?

Neither of the autoparts stores had them in stock or I would have tried

Re: LS3 water neck and radiator hose
 

I've had to splice pieces of hoses on some of the ones I've done..so that could be a option

Re: LS3 water neck and radiator hose
 

I replaced the lower outlet with a straight version. It was on my car, but it works well.

Re: LS3 water neck and radiator hose
 

I think the lower hose will work, ordered a GAtes 20931.... be here next week

Re: LS3 water neck and radiator hose
 

Yes that thermostat housing will work. I used the same one on my LS3. I would also use Mr. Gasket Thermostat, PN 6368.